放牧和模拟降水对短花针茅荒漠草原植物功能群多样性的影响     

刘欣蕊  崔媛媛  王忠武  孙海莲  韩国栋  侯东杰  王静  李治国  刘倬彤 《草地学报》2023,31(3):868-875

为探究放牧和降水变化对植物功能群的影响,本文以内蒙古短花针茅(Stipa breviflora)荒漠草原为研究对象,开展了野外控制试验。试验设置围封和适度放牧,分别进行模拟降水处理(减少降水量50%、自然降水、增加降水量50%、增加降水量100%),并在每年8月观测植物群落组成。结果表明：减水会降低植物功能群多样性、生物量和物种数量,增水有利于植物功能群多样性的提高。多年生丛生禾草多样性随降水量的增加而升高。同时,对降水梯度和功能群多样性进行拟合分析发现,降水量低于年降水量16%则不利于除灌木、半灌木外其他功能群植物的生长。围封草地增水67%～79%时,功能群的Simpson指数、Shannon-Wiener指数、Pielou指数值均较高,功能群多样性较高;由于放牧提高了植物的水分利用效率,放牧地各指数在增水26%～50%时较高,功能群多样性较高。综上,适度的放牧及水分补充有利于提高植物功能群多样性。  相似文献   

薄荷的快速繁殖与栽培技术的研究   总被引：3，自引：0，他引：3  

马春红陈霞翟彩霞  郭秀林崔四平李广敏 《中国农学通报》2004,20(4):230-230

本文介绍了薄荷的特性、栽培技术及用途，表明它在我们日常生活中起着重要的作用。用薄荷的组织培养方法可加速其繁殖系数，以达到迅速应用的目的。  相似文献   

p38MAPK信号通路选择性调节FSH对甾体生成 的诱导作用研究     

赵云焕  张自富  赵聘 《中国农学通报》2006,22(2):9-9

利用乙烯雌酚（DES）处理23日龄SD大鼠，分离卵巢颗粒细胞(GC)进行无血清培养。结果表明，FSH (50ng/m1) 处理GC，可迅速激活有丝分裂原蛋白激酶（p38 MAPK），FSH处理5min便可观察到磷酸化的p38 MAPK；FSH处理30min，磷酸化的p38 MAPK水平达到最高;向培养液中加入H89(蛋白激酶A抑制剂，10μM)，则显著抑制了FSH对p38 MAPK的激活作用，提示这种激活作用依赖于蛋白激酶A(PKA)。用 SB203580(p38MAPK抑制剂，20μM)抑制p38 MAPK激活，则进一步提高了FSH对孕酮和甾体生成快速调节蛋白（StAR）的诱导作用，同时降低了FSH对雌激素生成的促进作用(p<0.01)。RT-PCR结果显示：抑制p38 MAPK活性后，FSH对StAR mRNA刺激作用明显增强，但对细胞色素P450芳香化酶（P450arom）mRNA的诱导作用却减弱了(p<0.05)。激光共聚焦和蛋白印迹结果显示：在GC中，StAR蛋白主要分布在线粒体中；与对照组相比，FSH显著提高了StAR的荧光强度和蛋白水平；抑制p38MAPK活性则增强了FSH对StAR蛋白表达的诱导作用。  相似文献   

Respond of Stock Trading Volume to Earning Report     

FU Yun ying  MENG Wei dong  CUI Di 《保鲜与加工》2002,(11):79-82

Earning report is a main accounting report that transmits earning information to users. It is the core of financial reports system. Earning information is significant to users' decision making. This paper studies the respond of stock trading volume to earning report and draws the curve of trading volume before and after earning report. This paper further does a regression analysis of accidental earning and abnormal return rate, and draws the relation curve of them on the earning report date to prove stock trading volume does have remarkable respond to earning report. This research is significant to either lessen small investors blindness investment and help them make reasonable forecast to markets and regulate the disclosure of listed companies.  相似文献   

Reference Efficiency of Planetary Gear Train     

CUI Li  QIN Da-tong  SHI Wan-kai 《保鲜与加工》2006,(3):11

Reference efficiency of a pair of gear drive without planetary motion is the base to calculate efficiency of the whole planetary gear train. The authors find reference efficiency for speed increase is higher than that of the same drive used for speed reduction. This is different from the earlier viewpoint. New equations are derived for correctly calculating the reference efficiency of spur gear and helical gear with internal conjugate and external conjugate either in the state of speed increase or speed reduction respectively. The equations are also used to calculate efficiency of 2K-H planetary gear train.  相似文献   

Analysis on Longitudinal Cracks and Deflection of the Pre-stressed V-shape Slab Roof Structure     

YANG Hong-yuan  FAN Ze-bao  CUI Jia 《保鲜与加工》2002,(3):112-116

In this paper, the finite element method is used to analyze the behavior of the prestressed V-shape Slab Roof structure, especially the effect of temperature change on the stress of slab. The calculated results indicate that when the temperature changes, the tensile stress at the lower extreme fibers of the flange plate near rib exceeds the tensile strength of concrete subjected to the combined action of triaxial stresses and results in the longitudinal cracks of the flange plate. The deflection analysis is based on the mechanical model of the prestressed V shape slab with the longitudinal cracks. The calculated results are in general agreement with the field observations.  相似文献   

A Fast One-Step Scanning Thinning Algorithm     

Wu xiaoyun  Zhang Taiyi  Liu Pin 《保鲜与加工》1994,(3):13-17

A new quick thinning algorithm was presented in this paper,which assigneddifferent weights to different pixels near the skeleton pixels and rules out the im possible pixels in thethinning procedure. It needs neither iteration on pixel panel nor detection on every pixel such thatthe time consumed is greatly lessened. A filling algorithm is also offered for better results.Experiment on variety of binary patterns showed that it could get both a high speed and a goodskeleton shape compared with other algorithms,This new algorithm reaches perfect result.  相似文献   

Behavior and Design of High-strength Bolt in Tensile Connection     

CHENG Rui  CUI Ji  LONG Li-ping 《保鲜与加工》2002,(4):25-30

The tensile strength of high strength bolt is affected by many factors, including prying force. The prying force can result in the increment of bolt force, for which the connection failed ahead of time. Several methods are presented for calculating the prying force. In the China's "Code for Design of Steel Structure" (GB50017), there is no formula for calculation of prying force and a factor of 0.8 is considered in formula for tensile strength of bolt for taking the prying force into account. It is proposed that the design value of tensile resistance for high strength bolt should be increased.  相似文献   

单燃料燃气汽车发动机空燃比控制器设计     

崔宏宇  崔宏巍 《农机化研究》2006,(5):106-108

通过对单燃料燃气汽车发动机空燃比控制系统进行分析和研究,自行设计出了PI控制器,并且进行了仿真与实验研究。通过对燃气供给量的调整,保证发动机获得最佳性能,将空燃比精确地控制在理论值附近,在环境、温度发生变化和长期使用的情况下,仍能保证控制系统具有良好的性能。  相似文献   

灌溉试验站规划的有关问题   总被引：1，自引：0，他引：1  

王修贵  崔远来 《中国农村水利水电》2003,(11):8-12

根据全国的气候、农业、水利及经济发展水平等区划，合理地选择各省的中心站及重点试验站，并对其进行科学地规划设计，对于总体把握我国灌溉试验基础数据尤为重要。针对目前正在全国进行的灌溉试验站网规划，对省级中心站及重点站的课题规划、试验站的总体布置及设施设备规划和做好本次规划的其他有关问题进行了探讨。  相似文献